1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
use std::env;
use std::ffi::{OsStr, OsString};
use std::io::ErrorKind;
use std::mem;

use rustc_const_eval::interpret::Pointer;
use rustc_data_structures::fx::FxHashMap;
use rustc_middle::ty::layout::LayoutOf;
use rustc_target::abi::Size;

use crate::helpers::target_os_is_unix;
use crate::*;

/// Check whether an operation that writes to a target buffer was successful.
/// Accordingly select return value.
/// Local helper function to be used in Windows shims.
fn windows_check_buffer_size((success, len): (bool, u64)) -> u32 {
    if success {
        // If the function succeeds, the return value is the number of characters stored in the target buffer,
        // not including the terminating null character.
        u32::try_from(len.checked_sub(1).unwrap()).unwrap()
    } else {
        // If the target buffer was not large enough to hold the data, the return value is the buffer size, in characters,
        // required to hold the string and its terminating null character.
        u32::try_from(len).unwrap()
    }
}

#[derive(Default)]
pub struct EnvVars<'tcx> {
    /// Stores pointers to the environment variables. These variables must be stored as
    /// null-terminated target strings (c_str or wide_str) with the `"{name}={value}"` format.
    map: FxHashMap<OsString, Pointer<Option<Provenance>>>,

    /// Place where the `environ` static is stored. Lazily initialized, but then never changes.
    pub(crate) environ: Option<MPlaceTy<'tcx, Provenance>>,
}

impl VisitTags for EnvVars<'_> {
    fn visit_tags(&self, visit: &mut dyn FnMut(BorTag)) {
        let EnvVars { map, environ } = self;

        environ.visit_tags(visit);
        for ptr in map.values() {
            ptr.visit_tags(visit);
        }
    }
}

impl<'tcx> EnvVars<'tcx> {
    pub(crate) fn init<'mir>(
        ecx: &mut InterpCx<'mir, 'tcx, MiriMachine<'mir, 'tcx>>,
        config: &MiriConfig,
    ) -> InterpResult<'tcx> {
        let target_os = ecx.tcx.sess.target.os.as_ref();

        // Skip the loop entirely if we don't want to forward anything.
        if ecx.machine.communicate() || !config.forwarded_env_vars.is_empty() {
            for (name, value) in &config.env {
                let forward = ecx.machine.communicate()
                    || config.forwarded_env_vars.iter().any(|v| **v == *name);
                if forward {
                    let var_ptr = match target_os {
                        target if target_os_is_unix(target) =>
                            alloc_env_var_as_c_str(name.as_ref(), value.as_ref(), ecx)?,
                        "windows" => alloc_env_var_as_wide_str(name.as_ref(), value.as_ref(), ecx)?,
                        unsupported =>
                            throw_unsup_format!(
                                "environment support for target OS `{}` not yet available",
                                unsupported
                            ),
                    };
                    ecx.machine.env_vars.map.insert(name.clone(), var_ptr);
                }
            }
        }
        ecx.update_environ()
    }

    pub(crate) fn cleanup<'mir>(
        ecx: &mut InterpCx<'mir, 'tcx, MiriMachine<'mir, 'tcx>>,
    ) -> InterpResult<'tcx> {
        // Deallocate individual env vars.
        let env_vars = mem::take(&mut ecx.machine.env_vars.map);
        for (_name, ptr) in env_vars {
            ecx.deallocate_ptr(ptr, None, MiriMemoryKind::Runtime.into())?;
        }
        // Deallocate environ var list.
        let environ = ecx.machine.env_vars.environ.unwrap();
        let old_vars_ptr = ecx.read_pointer(&environ.into())?;
        ecx.deallocate_ptr(old_vars_ptr, None, MiriMemoryKind::Runtime.into())?;
        Ok(())
    }
}

fn alloc_env_var_as_c_str<'mir, 'tcx>(
    name: &OsStr,
    value: &OsStr,
    ecx: &mut InterpCx<'mir, 'tcx, MiriMachine<'mir, 'tcx>>,
) -> InterpResult<'tcx, Pointer<Option<Provenance>>> {
    let mut name_osstring = name.to_os_string();
    name_osstring.push("=");
    name_osstring.push(value);
    ecx.alloc_os_str_as_c_str(name_osstring.as_os_str(), MiriMemoryKind::Runtime.into())
}

fn alloc_env_var_as_wide_str<'mir, 'tcx>(
    name: &OsStr,
    value: &OsStr,
    ecx: &mut InterpCx<'mir, 'tcx, MiriMachine<'mir, 'tcx>>,
) -> InterpResult<'tcx, Pointer<Option<Provenance>>> {
    let mut name_osstring = name.to_os_string();
    name_osstring.push("=");
    name_osstring.push(value);
    ecx.alloc_os_str_as_wide_str(name_osstring.as_os_str(), MiriMemoryKind::Runtime.into())
}

impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
    fn getenv(
        &mut self,
        name_op: &OpTy<'tcx, Provenance>,
    ) -> InterpResult<'tcx, Pointer<Option<Provenance>>> {
        let this = self.eval_context_mut();
        this.assert_target_os_is_unix("getenv");

        let name_ptr = this.read_pointer(name_op)?;
        let name = this.read_os_str_from_c_str(name_ptr)?;
        Ok(match this.machine.env_vars.map.get(name) {
            Some(var_ptr) => {
                // The offset is used to strip the "{name}=" part of the string.
                var_ptr.offset(
                    Size::from_bytes(u64::try_from(name.len()).unwrap().checked_add(1).unwrap()),
                    this,
                )?
            }
            None => Pointer::null(),
        })
    }

    #[allow(non_snake_case)]
    fn GetEnvironmentVariableW(
        &mut self,
        name_op: &OpTy<'tcx, Provenance>, // LPCWSTR
        buf_op: &OpTy<'tcx, Provenance>,  // LPWSTR
        size_op: &OpTy<'tcx, Provenance>, // DWORD
    ) -> InterpResult<'tcx, Scalar<Provenance>> {
        // ^ Returns DWORD (u32 on Windows)

        let this = self.eval_context_mut();
        this.assert_target_os("windows", "GetEnvironmentVariableW");

        let name_ptr = this.read_pointer(name_op)?;
        let name = this.read_os_str_from_wide_str(name_ptr)?;
        Ok(match this.machine.env_vars.map.get(&name) {
            Some(var_ptr) => {
                // The offset is used to strip the "{name}=" part of the string.
                #[rustfmt::skip]
                let name_offset_bytes = u64::try_from(name.len()).unwrap()
                    .checked_add(1).unwrap()
                    .checked_mul(2).unwrap();
                let var_ptr = var_ptr.offset(Size::from_bytes(name_offset_bytes), this)?;
                let var = this.read_os_str_from_wide_str(var_ptr)?;

                let buf_ptr = this.read_pointer(buf_op)?;
                // `buf_size` represents the size in characters.
                let buf_size = u64::from(this.read_scalar(size_op)?.to_u32()?);
                Scalar::from_u32(windows_check_buffer_size(
                    this.write_os_str_to_wide_str(&var, buf_ptr, buf_size)?,
                ))
            }
            None => {
                let envvar_not_found = this.eval_windows("c", "ERROR_ENVVAR_NOT_FOUND")?;
                this.set_last_error(envvar_not_found)?;
                Scalar::from_u32(0) // return zero upon failure
            }
        })
    }

    #[allow(non_snake_case)]
    fn GetEnvironmentStringsW(&mut self) -> InterpResult<'tcx, Pointer<Option<Provenance>>> {
        let this = self.eval_context_mut();
        this.assert_target_os("windows", "GetEnvironmentStringsW");

        // Info on layout of environment blocks in Windows:
        // https://docs.microsoft.com/en-us/windows/win32/procthread/environment-variables
        let mut env_vars = std::ffi::OsString::new();
        for &item in this.machine.env_vars.map.values() {
            let env_var = this.read_os_str_from_wide_str(item)?;
            env_vars.push(env_var);
            env_vars.push("\0");
        }
        // Allocate environment block & Store environment variables to environment block.
        // Final null terminator(block terminator) is added by `alloc_os_str_to_wide_str`.
        let envblock_ptr =
            this.alloc_os_str_as_wide_str(&env_vars, MiriMemoryKind::Runtime.into())?;
        // If the function succeeds, the return value is a pointer to the environment block of the current process.
        Ok(envblock_ptr)
    }

    #[allow(non_snake_case)]
    fn FreeEnvironmentStringsW(
        &mut self,
        env_block_op: &OpTy<'tcx, Provenance>,
    ) -> InterpResult<'tcx, Scalar<Provenance>> {
        let this = self.eval_context_mut();
        this.assert_target_os("windows", "FreeEnvironmentStringsW");

        let env_block_ptr = this.read_pointer(env_block_op)?;
        let result = this.deallocate_ptr(env_block_ptr, None, MiriMemoryKind::Runtime.into());
        // If the function succeeds, the return value is nonzero.
        Ok(Scalar::from_i32(i32::from(result.is_ok())))
    }

    fn setenv(
        &mut self,
        name_op: &OpTy<'tcx, Provenance>,
        value_op: &OpTy<'tcx, Provenance>,
    ) -> InterpResult<'tcx, i32> {
        let this = self.eval_context_mut();
        this.assert_target_os_is_unix("setenv");

        let name_ptr = this.read_pointer(name_op)?;
        let value_ptr = this.read_pointer(value_op)?;

        let mut new = None;
        if !this.ptr_is_null(name_ptr)? {
            let name = this.read_os_str_from_c_str(name_ptr)?;
            if !name.is_empty() && !name.to_string_lossy().contains('=') {
                let value = this.read_os_str_from_c_str(value_ptr)?;
                new = Some((name.to_owned(), value.to_owned()));
            }
        }
        if let Some((name, value)) = new {
            let var_ptr = alloc_env_var_as_c_str(&name, &value, this)?;
            if let Some(var) = this.machine.env_vars.map.insert(name, var_ptr) {
                this.deallocate_ptr(var, None, MiriMemoryKind::Runtime.into())?;
            }
            this.update_environ()?;
            Ok(0) // return zero on success
        } else {
            // name argument is a null pointer, points to an empty string, or points to a string containing an '=' character.
            let einval = this.eval_libc("EINVAL")?;
            this.set_last_error(einval)?;
            Ok(-1)
        }
    }

    #[allow(non_snake_case)]
    fn SetEnvironmentVariableW(
        &mut self,
        name_op: &OpTy<'tcx, Provenance>,  // LPCWSTR
        value_op: &OpTy<'tcx, Provenance>, // LPCWSTR
    ) -> InterpResult<'tcx, Scalar<Provenance>> {
        let this = self.eval_context_mut();
        this.assert_target_os("windows", "SetEnvironmentVariableW");

        let name_ptr = this.read_pointer(name_op)?;
        let value_ptr = this.read_pointer(value_op)?;

        if this.ptr_is_null(name_ptr)? {
            // ERROR CODE is not clearly explained in docs.. For now, throw UB instead.
            throw_ub_format!("pointer to environment variable name is NULL");
        }

        let name = this.read_os_str_from_wide_str(name_ptr)?;
        if name.is_empty() {
            throw_unsup_format!("environment variable name is an empty string");
        } else if name.to_string_lossy().contains('=') {
            throw_unsup_format!("environment variable name contains '='");
        } else if this.ptr_is_null(value_ptr)? {
            // Delete environment variable `{name}`
            if let Some(var) = this.machine.env_vars.map.remove(&name) {
                this.deallocate_ptr(var, None, MiriMemoryKind::Runtime.into())?;
                this.update_environ()?;
            }
            Ok(this.eval_windows("c", "TRUE")?)
        } else {
            let value = this.read_os_str_from_wide_str(value_ptr)?;
            let var_ptr = alloc_env_var_as_wide_str(&name, &value, this)?;
            if let Some(var) = this.machine.env_vars.map.insert(name, var_ptr) {
                this.deallocate_ptr(var, None, MiriMemoryKind::Runtime.into())?;
            }
            this.update_environ()?;
            Ok(this.eval_windows("c", "TRUE")?)
        }
    }

    fn unsetenv(&mut self, name_op: &OpTy<'tcx, Provenance>) -> InterpResult<'tcx, i32> {
        let this = self.eval_context_mut();
        this.assert_target_os_is_unix("unsetenv");

        let name_ptr = this.read_pointer(name_op)?;
        let mut success = None;
        if !this.ptr_is_null(name_ptr)? {
            let name = this.read_os_str_from_c_str(name_ptr)?.to_owned();
            if !name.is_empty() && !name.to_string_lossy().contains('=') {
                success = Some(this.machine.env_vars.map.remove(&name));
            }
        }
        if let Some(old) = success {
            if let Some(var) = old {
                this.deallocate_ptr(var, None, MiriMemoryKind::Runtime.into())?;
            }
            this.update_environ()?;
            Ok(0)
        } else {
            // name argument is a null pointer, points to an empty string, or points to a string containing an '=' character.
            let einval = this.eval_libc("EINVAL")?;
            this.set_last_error(einval)?;
            Ok(-1)
        }
    }

    fn getcwd(
        &mut self,
        buf_op: &OpTy<'tcx, Provenance>,
        size_op: &OpTy<'tcx, Provenance>,
    ) -> InterpResult<'tcx, Pointer<Option<Provenance>>> {
        let this = self.eval_context_mut();
        this.assert_target_os_is_unix("getcwd");

        let buf = this.read_pointer(buf_op)?;
        let size = this.read_scalar(size_op)?.to_machine_usize(&*this.tcx)?;

        if let IsolatedOp::Reject(reject_with) = this.machine.isolated_op {
            this.reject_in_isolation("`getcwd`", reject_with)?;
            this.set_last_error_from_io_error(ErrorKind::PermissionDenied)?;
            return Ok(Pointer::null());
        }

        // If we cannot get the current directory, we return null
        match env::current_dir() {
            Ok(cwd) => {
                if this.write_path_to_c_str(&cwd, buf, size)?.0 {
                    return Ok(buf);
                }
                let erange = this.eval_libc("ERANGE")?;
                this.set_last_error(erange)?;
            }
            Err(e) => this.set_last_error_from_io_error(e.kind())?,
        }

        Ok(Pointer::null())
    }

    #[allow(non_snake_case)]
    fn GetCurrentDirectoryW(
        &mut self,
        size_op: &OpTy<'tcx, Provenance>, // DWORD
        buf_op: &OpTy<'tcx, Provenance>,  // LPTSTR
    ) -> InterpResult<'tcx, Scalar<Provenance>> {
        let this = self.eval_context_mut();
        this.assert_target_os("windows", "GetCurrentDirectoryW");

        let size = u64::from(this.read_scalar(size_op)?.to_u32()?);
        let buf = this.read_pointer(buf_op)?;

        if let IsolatedOp::Reject(reject_with) = this.machine.isolated_op {
            this.reject_in_isolation("`GetCurrentDirectoryW`", reject_with)?;
            this.set_last_error_from_io_error(ErrorKind::PermissionDenied)?;
            return Ok(Scalar::from_u32(0));
        }

        // If we cannot get the current directory, we return 0
        match env::current_dir() {
            Ok(cwd) =>
                return Ok(Scalar::from_u32(windows_check_buffer_size(
                    this.write_path_to_wide_str(&cwd, buf, size)?,
                ))),
            Err(e) => this.set_last_error_from_io_error(e.kind())?,
        }
        Ok(Scalar::from_u32(0))
    }

    fn chdir(&mut self, path_op: &OpTy<'tcx, Provenance>) -> InterpResult<'tcx, i32> {
        let this = self.eval_context_mut();
        this.assert_target_os_is_unix("chdir");

        let path = this.read_path_from_c_str(this.read_pointer(path_op)?)?;

        if let IsolatedOp::Reject(reject_with) = this.machine.isolated_op {
            this.reject_in_isolation("`chdir`", reject_with)?;
            this.set_last_error_from_io_error(ErrorKind::PermissionDenied)?;

            return Ok(-1);
        }

        match env::set_current_dir(path) {
            Ok(()) => Ok(0),
            Err(e) => {
                this.set_last_error_from_io_error(e.kind())?;
                Ok(-1)
            }
        }
    }

    #[allow(non_snake_case)]
    fn SetCurrentDirectoryW(
        &mut self,
        path_op: &OpTy<'tcx, Provenance>, // LPCTSTR
    ) -> InterpResult<'tcx, Scalar<Provenance>> {
        // ^ Returns BOOL (i32 on Windows)

        let this = self.eval_context_mut();
        this.assert_target_os("windows", "SetCurrentDirectoryW");

        let path = this.read_path_from_wide_str(this.read_pointer(path_op)?)?;

        if let IsolatedOp::Reject(reject_with) = this.machine.isolated_op {
            this.reject_in_isolation("`SetCurrentDirectoryW`", reject_with)?;
            this.set_last_error_from_io_error(ErrorKind::PermissionDenied)?;

            return this.eval_windows("c", "FALSE");
        }

        match env::set_current_dir(path) {
            Ok(()) => this.eval_windows("c", "TRUE"),
            Err(e) => {
                this.set_last_error_from_io_error(e.kind())?;
                this.eval_windows("c", "FALSE")
            }
        }
    }

    /// Updates the `environ` static.
    /// The first time it gets called, also initializes `extra.environ`.
    fn update_environ(&mut self) -> InterpResult<'tcx> {
        let this = self.eval_context_mut();
        // Deallocate the old environ list, if any.
        if let Some(environ) = this.machine.env_vars.environ {
            let old_vars_ptr = this.read_pointer(&environ.into())?;
            this.deallocate_ptr(old_vars_ptr, None, MiriMemoryKind::Runtime.into())?;
        } else {
            // No `environ` allocated yet, let's do that.
            // This is memory backing an extern static, hence `ExternStatic`, not `Env`.
            let layout = this.machine.layouts.mut_raw_ptr;
            let place = this.allocate(layout, MiriMemoryKind::ExternStatic.into())?;
            this.machine.env_vars.environ = Some(place);
        }

        // Collect all the pointers to each variable in a vector.
        let mut vars: Vec<Pointer<Option<Provenance>>> =
            this.machine.env_vars.map.values().copied().collect();
        // Add the trailing null pointer.
        vars.push(Pointer::null());
        // Make an array with all these pointers inside Miri.
        let tcx = this.tcx;
        let vars_layout = this.layout_of(
            tcx.mk_array(this.machine.layouts.mut_raw_ptr.ty, u64::try_from(vars.len()).unwrap()),
        )?;
        let vars_place = this.allocate(vars_layout, MiriMemoryKind::Runtime.into())?;
        for (idx, var) in vars.into_iter().enumerate() {
            let place = this.mplace_field(&vars_place, idx)?;
            this.write_pointer(var, &place.into())?;
        }
        this.write_pointer(vars_place.ptr, &this.machine.env_vars.environ.unwrap().into())?;

        Ok(())
    }

    fn getpid(&mut self) -> InterpResult<'tcx, i32> {
        let this = self.eval_context_mut();
        this.assert_target_os_is_unix("getpid");

        this.check_no_isolation("`getpid`")?;

        // The reason we need to do this wacky of a conversion is because
        // `libc::getpid` returns an i32, however, `std::process::id()` return an u32.
        // So we un-do the conversion that stdlib does and turn it back into an i32.
        #[allow(clippy::cast_possible_wrap)]
        Ok(std::process::id() as i32)
    }

    #[allow(non_snake_case)]
    fn GetCurrentProcessId(&mut self) -> InterpResult<'tcx, u32> {
        let this = self.eval_context_mut();
        this.assert_target_os("windows", "GetCurrentProcessId");

        this.check_no_isolation("`GetCurrentProcessId`")?;

        Ok(std::process::id())
    }
}